Not only that, but the newly minted Canon 550D has nearly the same ISO performance as the Nikon [D5000] and 20% greater resolution—the cost of that resolution is a one stop worse dynamic range

(The Nikon D5000 and D90 have the same sensor design.)

This is the problem with reviews snippets taken in isolation: the Canon 550D and the Nikon D90 are nearly the same (street) price so it may seem that the Nikon D90 is a bad value but this isn’t the case at all. The Nikon D5000 is much cheaper than the Canon 550D and delivers the same ISO performance as the D90, are we to say the 550D is a bad value then? The Canon 550D has the same sensor as the Canon 7D are we to say that the Canon 7D is a rip off?

No. Because the Nikon D90 has a much, much brighter viewfinder and better dynamic range than the Canon 550D—in turn the Canon 550D has a better video mode and higher resolution than the D90. And the Canon 7D tops the D90 with even all-metal construction and a 100% viewfinder (both notoriously expensive to manufacture). Here is a small table:

(As for JPEG, that’s a post-processing design decision. Did you know that Nikon’s tend to be undersharpened and have more faithful red channel color? So what.)

The table shows you that basically these cameras have a price interleave that is nearly exactly right. The D90 is the 550D with different tradeoffs; the D300S is the the 7D with tradeoffs. The D90/550D give up similar things to the D300S/7D. I mentioned this before. When it comes to sensors, Nikons tend to have better ISO and dynamic range but at the cost of resolution. I also mentioned this before.

This sort of pixel peeping is going to give you the exact same result that a Nikon D3000S/Canon 7D comparison gave you last year. I bet if I tested resolution at low ISO the Canon would win; if I tested dynamic range, the Nikon would win. Yawn!